ah, I'm not really interested in lucasarts.

If it's not LucasArts, then the only real option would be The Longest Journey. Even if you consider other adventure-related genres (like RPGs), you get the following options:
System Shock 2
Thief: The Dark Project
Splinter Cell Chaos Theory
Splinter Cell
Planescape: Torment
The Longest Journey
A nice list indeed, but the only game in that list that fits in "lots of people haven't heard of it" is TLJ. Maybe Planescape: Torment would fit, but I don't think GOG would announce it as an adventure, so there you have it.

Hence why I said "even if you consider other adventure-related genres (like RPGs), you get the following options". Keep in mind that GOG never said that the "adventure" classification is the Metacritic one - in the game catalogue, among the games classified as "adventure" in GOG, you'll find the following:
Arx Fatalis
Die By The Sword
Duke Nukem: Manhattan Project
Earthworm Jim
Gothic 2
Prince of Persia: Sands of Time
If that's not "stretching", I don't know what it is. :-)
Also, allow me to point out what I said right after the said list in my original post:
"A nice list indeed, but the only game in that list that fits in "lots of people haven't heard of it" is TLJ."
So, can we agree to agree? ;-)

So hypotheticaly speaking, how good is TLJ?
I've been meaning to buy it...

Unless you have a 64-bit operating system you can play Psychonauts free on GameTap.

And therein lies the catch.

Without exaggerating, I'd say it is super awesome. I'll buy it again if it is released here.

I'm on board that train aswell.
I have two versions already but i'd get gog's version faster than you can say 'drm sucks' :)

Thirded.

I'll board a slightly different train and say the writing, story and voiceacting is super awesome, but the puzzles are, by and large, stupid.

The rubber ducky gave you a hard time, eh ? :)

YOU JUST RUINED THE WHOLE GAME FOR ME

Gabriel Knight series.

Strong deslike for rubber duckyes ?